Molecular Orientation and Periodical Structure of Vacuum-Deposited Films of Long-Chain Molecules

The molecular orientation and periodical structure of vacuum-deposited films of n-alkanes and low-molecular-weight polyethylenes were investigated using the wide-angle X-ray diffraction (WAXD) method. The gel permeation chromatography (GPC) measurement indicated that chain shortening occurred in the vacuum-deposited film of polyethylenes with molecular weight higher than 700. From the comparison of WAXD data with GPC data, it was found that the extended chain, rather than the folded chain, is dominant in normal-oriented polyethylene films, though the chain shortening takes place during the vapor deposition process.